1. Field of the Invention
The present invention relates to an apparatus and method for separating two phase-modulated signals having different amplitudes.
2. Description of the Related Art
Amplitude modulation refers to a modulation method of changing an amplitude of carrier based on strength of an information signal and may be weak against multipath fading due to a multipath of propagation and may have a high peak-to-average power ratio (PAPR). However, phase modulation may carry an information signal using a phase of carrier and thereby transmit the information signal and thus, may have a consistent amplitude of carrier. The phase modulation may have a relatively excellent noise characteristic compared to the amplitude modulation. Further, the phase modulation may have a significantly low PAPR, and may require a relatively wide transmission bandwidth compared to the amplitude modulation.
In general, a high PAPR may cause a nonlinear distortion in a power amplifier of a transmitter. Unless sufficient backoff is not given with respect to power, a frequency spectrum of a system may be widened and a distortion by mutual modulation between frequencies may occur, which may result in degrading the system performance.